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Hair/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A boy, Tim, and a robot, Moby, are in a school science lab. Moby is doing an experiment involving a Bunsen burner and a beaker of fluid. Tim watches with curiosity. TIM: Whatcha doin'? MOBY: Beep. Moby holds up the beaker and examines it. Then he drinks from it. Hair suddenly grows from the top of his head down to the floor, covering his entire face and body. Only his eyes are visible. MOBY: Beep. Moby's arm reaches out from beneath his floor-length hair. He hands Tim a sheet of paper. Tim reads from a typed letter. TIM: Dear Tim and Moby, why do we have hair? Signed, Lulu. Growing hair is part of your body's natural processes. All mammals have some form of hair or fur on their bodies. An image shows a bear, a monkey, a cat, and a squirrel. All of them have fur. TIM: Mammals are warm-blooded, and that fur helps maintain their body temperature. Warmblooded animals regulate their own body temperatures. An animation shows a squirrel with little or no fur. It shivers. Then fur appears on its body, and it stops shivering. TIM: That's why your temperature is usually around 98.6 degrees Fahrenheit, whether it's January or June. Mammals without fur, like whales, insulate their bodies with layers of fat. An image shows a whale swimming underwater. TIM: But even whales have some hair, sometimes on their jaws and lips. MOBY: Beep. A mustache and beard appear on the whale's face. TIM: Uh, I don't think it looks exactly like that. Anyway, humans are mammals, too. And our ancestors started out with hair all over their bodies. Moby still has floor-length hair, but his face and body are now visible. TIM: But as we evolved over the last million years or so, we gradually lost most of our body hair. An image represents the transitional forms between apelike creature and human being. The first creature is covered in hair, while the last has very little noticeable hair. TIM: Actually, our hair just became less thick and coarse. If you look closely, you'll see that most of your body is still covered in hair. In humans, hair comes in three basic types. There's lanugo hair, which is a fine, lightly colored hair that covers your body when you're a baby. An image shows a crying baby. TIM: Then there's vellus hair. It's basically like peach fuzz, light in color and no longer than an inch. An image shows a close-up of skin withshort vellus hair growing on it. TIM: You can find it on the undersides of your arms and lots of other places on your body. Women tend to have more vellus hair than men, by the way. MOBY: Beep. Moby admires the long hair growing from his head. TIM: Nope, that's not vellus hair you've got there, buddy. That's terminal hair. Terminal hair is thick and dark. It's your head hair, for one thing. And after you've gone through puberty, you'll also find it on your arms, legs, armpits, pubic areas, and, if you're a guy, your beard and chest. Here's how it grows. Before you're born, hair follicles form in your skin. You've got about a hundred thousand of these on your head alone. Follicles are sort of like little pouches. At the bottom are a bunch of cells that divide rapidly. An image appears of a single hair and its follicle, under the skin. TIM: As new cells are made, the older cells are pushed out of the follicle. Eventually, they're pushed all the way up to, and then out of, the surface of your skin. An animation shows the process Tim describes. Several hairs grow from a patch of human skin. MOBY: Beep. TIM: No, you can't feel it happening. Believe it or not, the only living hair cells you have are down at the base of the follicles. The hair that you can see is all dead matter. It's mostly made of a protein called keratin. MOBY: Beep. TIM: Well, if you look at a cross-section, the hair actually has three parts. The outermost layer is called the cuticle, and it's sort of like a protective coating. Inside are the cortex, and sometimes the medulla. The cortex gives hair its strength and coloring, and researchers aren't quite sure what the medulla does. The finer hairs on your body don't have medullas, and if you have naturally blond hair, you don't have medullas at all. An image shows a cross-section of a human hair. Labels appear that indicate the cuticle, cortex, and medulla. TIM: Each follicle also contains something called a sebaceous gland. It produces an oily substance called sebum, which prevents your hair from becoming dry and brittle. An image shows a sebaceous gland, a pouch-like structure near the base of a hair and beneath the skin, and the sebum that comes from it. TIM: Also, if you don't wash your hair for a few days, sebum can make it feel gross and oily. MOBY: Beep. Moby scratches his scalp, looking concerned. TIM: Well, some people have curved follicles. When their hair grows, it comes out curly. Other people have follicles that are straight and perpendicular to the surface of their scalp. Their hair grows straight. Animations compare a curved follicle to a straight one. Images show a young lady with curly hair and another young lady with straight hair. MOBY: Beep. TIM: Oh, color? Well, that's determined by your genes, which you inherit from your parents. You know, the hair on your body grows as long as you're alive. And yeah, remember not to freak out when you start to see hair growing in some strange places. It's a perfectly normal part of growing up. MOBY: Beep. TIM: No, I don’t think robots go through puberty. MOBY: Beep beep. Moby's beep is deeper than normal. TIM: Wow, I guess your voice is changing. Category:BrainPOP Transcripts Category:BrainPOP Health Transcripts